Warn users of rename risks using download statistics

The risk of vacating a namespace primarily relates to a situation where a popular project is replaced with a malicious project that users will unintentionally clone through an out of date link or an automation script. In many cases projects are not sufficiently popular that this would be a problem.

GitLab can help project maintainers avoid this by providing feedback about the impact of a rename, and instructions for renaming a project in a safe way.

Proposal

When attempting to rename a project, show the user:

number of unique cloners for last 30 days
number of anonymous clones for the last 30 days
number of archive downloads for the last 30 days

If these numbers indicate frequent anonymous clones and archive downloads, this would indicate the user should be careful about renaming the project.

Provide a link to documentation of best practice for moving or renaming popular projects

Links

https://gitlab.com/gitlab-org/gitlab-ce/issues/21743 https://gitlab.com/gitlab-org/gitlab-ce/issues/35446